1. Field of the Invention
The present invention relates to a muffler adapted to be connected to an exhaust system of an engine, and more particularly to a muffler suitable for an automotive engine by enhancing the noise reduction effect while avoiding enlargement and flattening of the muffler""s shell.
2. Description of the Related Art
A conventional muffler, connected to an exhaust system of an automotive engine, includes an inlet pipe, an outlet pipe, and an expansion chamber. The inlet pipe is continuously connected to an exhaust pipe from the engine, whereas the outlet pipe is open to the atmosphere. The expansion chamber provides communication between the inlet pipe and the outlet pipe. It is known that extending the length of the muffler""s outlet pipe enhances the noise reduction effect on the exhaust noise. If the outlet pipe simply is extended, however, then a downstream portion of the outlet pipexe2x80x94or a tail pipexe2x80x94largely extends rearward from a shell of the muffler. If one attempts to apply such a mufflerxe2x80x94with the outlet pipe so extendedxe2x80x94to an engine of an automobile, then there is a risk that the tail pipe may interfere with a device of the automobile, such as the automobile""s rear bumper. Thus, space for the muffler is limited, whereby it is difficult to extend the outlet pipe outwardly from the muffler""s shell.
To cope with this, there have been proposed ways for extending the outlet pipe within the shell. For example, well known are: disposing an outlet pipe in a U-shaped fashion within a shell (refer to JP-A-55-59119U); and disposing an outlet pipe in an S-shaped fashion within a shell (JP-B-2-41293U).
When an outlet pipe is extended within a shell of a muffler as described above, however, the diameter of the muffler increases. More particularly, when the outlet pipe is S-shaped within the shell, as is the case with the aforesaid conventional example, the respective straight pipe portions of the outlet pipe are disposed in the same plane. Therefore, a diameter of the shell of the mufflerxe2x80x94in the direction of the plane in which the pipe portions are disposedxe2x80x94increases. Accordingly, the shell of the muffler is flatter, which leads to the reduction of rigidity in the face of the shell, and which causes problems such as: necessity of a separate reinforcement means; and the shell of the muffler becomes lager in size.
The present invention was made in view of the foregoing situations, and a primary object thereof is to provide a novel muffler that can solve the aforesaid problems by improving the construction of an outlet pipe disposed in the muffler""s shell.
With a view to attaining the above and other objects, according to a first aspect of the invention, there is provided a muffler, for an engine, comprising:
a shell;
an inlet pipe provided in said shell and connected to an exhaust pipe from said engine; and
an outlet pipe provided in said shell, and open to the atmosphere, said outlet pipe including:
three linear pipe portions defining an exhaust gas inlet pipe portion, an exhaust gas return pipe portion, and an exhaust gas outlet pipe portion; and
two turnaround pipe portions that are curved so as to connect said linear pipe portions to each other in series,
wherein said exhaust gas inlet pipe portion, said exhaust gas return pipe portion, and said exhaust gas outlet pipe portion, are disposed in parallel with each other along a longitudinal direction of said shell,
further wherein longitudinal axes of said three linear pipe portions are positioned on respective vertices of a triangle, and
further wherein said exhaust gas inlet pipe portion is disposed adjacent to a bottom portion of said shell.
According to such construction, there is no need to make the shell of the muffler flatter and larger, and water remaining trapped in the muffler shell easily is drained therefrom.
In addition, according to a second aspect of the invention, there is provided a muffler for an engine as set forth in the first aspect of the invention, wherein exhaust noise interference holes are formed in an upper area of an intermediate portion of the outlet pipe, whereby the holes open the interior of the outlet pipe to the interior of the shell. Accordingly, there is no need to make the shell of the muffler flatter and larger, and water remaining trapped in the muffler shell easily can be drained therefrom. In addition, the resonance of exhaust noise within the outlet pipe effectively can be prevented. Moreover, there is no risk of water remaining trapped in the outlet pipe and returning to the shell through the exhaust noise interference holes.